Method for optical transmission of a structure into a recording medium

Abstract

A method for optical transmission of a structure into a recording medium which can be transformed locally from a first undefined state into a second defined state by irradiating with photons from a photon source. The two states of the recording medium are manifested in different physical and / or chemical properties of the recording medium. At least one photon source having a photon flux of less than 104 photons per second is selected for the irradiation with the photons. It was recognized that with such a low photon flux especially fine structures can advantageously be transmitted into the recording medium without the irradiation having to be partially blocked by a mask. In this manner, for a given wavelength (energy) of the photons, structures can be transmitted that are considerably smaller than the width, defined by the diffraction limit, of the probability distribution for the locations at which the emitted photons are incident.

Description

BACKGROUND OF THE INVENTION[0001]Microstructures and nanostructures are usually created by means of optical lithography. The substrate to be structured is first overlaid with a recording medium. The structure to be created is imparted to this recording medium by locally irradiating the recording medium with light through a mask. It is thereby transformed from an unwritten into a written state which is manifested in altered physical and / or chemical properties of the recording medium. The recording medium is then selectively removed either only at the written sites or only at the unwritten sites, whereupon the substrate can be processed, for instance etched, at the exposed sites.[0002]The minimum size of the structures to be written is defined, for diffraction reasons, by the order of magnitude of the light wavelength. Therefore, in order to reduce the size of the structures, i.e. to improve the spatial resolution, the light wavelength used must be increasingly further reduced. The ti...

AI Technical Summary

Benefits of technology

This approach eliminates the need for masks, achieving spatial resolutions closer to the diffraction limit, enabling the creation of smaller structures without the need for smaller wavelengths and reducing manufacturing complexity and cost.

Problems solved by technology

These disadvantages together lead to the situation whereby the spatial resolution that can be achieved in practice in lithography is often much worse than the diffraction limit by about half a light wavelength.A mask usually consists of a laterally structured light-impermeable layer, for example a chromium layer, which serves as the structure to be written and is in turn applied to a light-permeable substrate.

The greater this distance, the greater the smearing of the written structure due to the distributions, of only finite sharpness, of the energies and irradiation directions among the photons used.Further diffraction effects occur at the structure edges of the light-impermeable layer, which likewise leads to a smearing of the written structure.The mask can be created only with finite precision, which leads to further uncertainty with regard to the precise dimensions of the written structure.A mask having macroscopic dimensions, for instance the dimensions of a typical semiconductor wafer having a diameter of several inches, is usually irradiated by an expansive light source, for instance a lamp.

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